Warning: Array to string conversion in entity_embed/src/Form/EntityEmbedDialog.php on line 839

Problem/Motivation

Having the following issue when trying to embed an image:

{
    "message": "\nTapahtui AJAX HTTP virhe.\nHTTP koodi: 200\nSeuraavassa virhetiedot.\nPolku: /fi/entity-embed/dialog/filtered_html/embed_media?_wrapper_format=drupal_ajax&ajax_form=1\nTilanneteksti: parsererror\nVastausteksti: Warning: Array to string conversion in /app/drupal/web/modules/contrib/entity_embed/src/Form/EntityEmbedDialog.php on line 839\n[{\"command\":\"editorDialogSave\",\"values\":{\"entity\":\"\",\"attributes\":{\"data-entity-type\":\"media\",\"data-entity-uuid\":\"d5b4558e-3259-4b92-8864-9e04e3c62812\",\"data-entity-embed-display\":\"view_mode:media.body_image\",\"data-entity-embed-display-settings\":[],\"data-embed-button\":\"embed_media\",\"data-caption\":\"Test123\"},\"actions\":{\"back\":\"Takaisin\",\"save_modal\":\"Upota\"},\"form_build_id\":\"form-699FKYWj-uBVetNxdcFfKMrJjehAc63KvzDOg-PGAKI\",\"form_token\":\"2vucL_aw-LJliEujzl2u5zp7hVSYRnN7o",
    "name": "AjaxError"
}